2010 “Too Many Catches? Consumption, Habitat, Climate, and Competition in Medieval European Fisheries” , an invited public lecture in the 2010 Saul O. Sidore lecture series entitled ‘Sea Stories for the Future: Interdisciplinary Conversations on Historic Oceans and Contemporary Marine Science’ at the Center for the Humanities, University of New Hampshire, Durham, NH, 27 October.

2009 “Bugs, Beasts, and Business: Some Everyday and Long-Term Interactions in Preindustrial Europe,” an invited lecture at the XLI Settimana di Studi of the Istituto Internazionale di Storia Economica “F. Datini”: Le interazioni fra economia e ambiente biologico nell’Europa preindustriale. Secc. XIII-XVIII / Economic and Biological Interactions in the Pre-industrial Europe from the 13th to the 18th Centuries, Prato, 26-30 April

2009 “Fisheries Protection and State Authority on the Late Medieval Danube: Contextualizing the Imperial Patent of 1506" in a panel on ‘Imagined abundance and ecological realities: Dealing with aquatic resources in late medieval Europe’ at the annual meeting of the American Society for Environmental History, Tallahassee, Florida, Feb 26-Mar 1.

2009 “Puzzling out medieval herring from a pan-European perspective” st the 15th Fish Remains Working Group International Congress of Archaeozoology, Poznań-Toruń, Poland, 3-9 September.

2008 "Elemental Resources and Aquatic Ecosystems: Medieval Europeans and their Rivers" an invited lecture at the international workshop "The Way the Rivers Run: World History and Changes in the Water Landscape", sponsored by the Centre for Advanced Study at the Norwegian Academy of Science and Letters in Oslo, 2008 November 17-18.

2008 “Nature and Culture, Culture and Nature, in the Middle Ages and in Medieval Studies” an invited keynote lecture at the International Medieval Congress 2008 at the University of Leeds, 2008 July 7-10. Revised for delivery in a series of lectures in Medieval Studies at the University of Waterloo, 2008 Nov 27. Further revised for presentation to the Institute of History, Polish Academy of Sciences, Warsaw, 2009 Sept 10.

2008 “Puzzling out medieval herring from a European perspective”, a paper for the 37th Annual University of British Columbia Medieval Workshop, Vancouver, 2008 April 2-3. Revised for delivery to the Quelque Arpents de Niege workshop of environmental historians in Canada, held at the University of Toronto, 2008 December 12.

2007 “Aquaculture in Champagne before the Black Death (1348-50)” a paper for the biennial meeting of the Fish Remains Working Group, International Congress of Archaeozoology, Antibes, France, 2007 October 18-20.

2007 “Connecting Traditional Aquaculture to Land, Water, and Agroecosystems,” a paper for the panel entitled “Soils, woods, waters: Ecological connections maintaining productivity and creating traditional European agroecosystems” at the biennial meeting of the European Society for Environmental History, Amsterdam, 2007 June 5-9.

2007 “Medieval European Fisheries: Archaeological and historical evidence for some indicator species,” an invited lecture at Institut Maurice-Lamontagne / Maurice Lamontagne Institute, Fisheries and Oceans Canada, Mont Joli, Quebec, March 30.

2007 “Medieval Europeans and Their Aquatic Ecosystems,” an invited lecture at Graduierte Kolleg: Interdiziplinäre Umweltgeschichte – Naturale Umwelt und gesellschaftliches Handeln in Mitteleuropa, Georg August Universität, Göttingen, Germany, May 23.

2007 panelist (and organizer) in “Round Table: Doing Environmental History Outside the Modern Age: Problems and Paradigms” at the annual meeting of the American Society for Environmental History, Baton Rouge, LA, 2007 February 28- March 3.

2006 co-author with Verena Winiwarter, “Making Land and Water Meet: Cycling of Nutrients between Fields and Ponds in Pre-Modern Europe,” a paper for the annual meeting of the Social Science History Association, Minneapolis, MN, 2006 November 1-4.

2005 co-author with Bernd Herrmann et al. of "Abundance of Species in Historic Times: Report of an ad-hoc research group" at the 3d meeting of the European Society for Environmental History, Florence, Italy, 16-19 February 2005.

2005 "Aquatic Commons in worlds of change: Medieval European experiences and present-day management issues" an invited lecture at the Zentrum für Umweltgeschichte of the Fakultät für Interdisziplinäre Forschung und Fortbildung, Universität Klagenfurt in Wien, Vienna, 2005 October 17. Repeated at the meeting of the Quelque Arpents de Neige workshop of environmental historians in Canada, held at the University of Western Ontario, 2005 December 9.

2005 panelist in Round Table "Teaching Environmental History" at the annual meeting of the Canadian Historical Association, University of Western Ontario, 31 May 2005.

2005 "Strekfusz: a competitor to imported stockfish in late medieval eastern Europe", a paper for the 13th Fish Remains Working Group Meeting, International Council for Archaeozoology, Basel, Switzerland, 5-9 October 2005.

2004 "Aquatic Resource Use in Medieval Europe", an invited contribution to an international workshop "Ecological History of the Wadden Sea: 2000 years of human-induced change in a unique coastal ecosystem" at the Wadden Sea Field Research Station, List, Sylt, of the Alfred-Wegener-Institute of Polar and Marine Research, Universität Kiel, 2004 January 22-25.

2004 "Footprint metaphor and metabolic realities: Environmental impacts of medieval urbanism", an invited lecture at the Zentrum für Umweltgeschichte of the [Austrian interuniversity] Fakultät für Interdisziplinäre Forschung und Fortbildung--Wien, Vienna, 2004 June 28.

2004 "Homo et Natura, Homo in Natura: Ecological Perspectives on the European Middle Ages," an invited lecture to open a public series on "Nature in the Middle Ages and the Renaissance" at the Center for Medieval and Renaissance Studies, Ohio State University, 2004 October 15

2003 "Ecological Footprints of Medieval Cities" in a session on "Medieval Landscapes" at the 2d Meeting of the European Society for Environmental History, Prague, 2003 September 3-6.

2003 "The 'Ecological Footprint' of Medieval European Cities", an invited contribution to an international conference on 'Natures Past: Comparative Perspectives on Environmental Change" sponsored by Comparative Studies in Society and History at the University of Michigan, Ann Arbor, 2003 October 3-4.

2002 "Beyond the Limits: Ecological Footprints of Medieval Cities" at an interdisciplinary conference "City Limits: Urban Culture in the Middle Ages" of the Centre for Medieval Studies, University of Toronto, 2002 March 2.

2002 “Medieval Europeans and their Aquatic Ecosystems,” an invited contribution to a symposium “Historical Perspectives on Natural History and Ecology” at the 83d Annual Meeting of the Western Society of Naturalists, Monterey, California, 2002 November 8-11.

2001 “Aquaculture and the Engineering of Landscapes in Medieval Europe” in a session on “Long Term Landscape History in Europe” at the annual meeting of the American Society for Environmental History, Durham, N.C., March-April 2001

2001 “Deep History in Some Marine Coastal Environments”, an invited paper in a special session on “Marine Environmental History: Shifting Baselines and Conservation Targets” at the Second Symposium on Marine Conservation Biology sponsored by the Marine Conservation Biology Institute, San Francisco State University, June 2001.

1999 “A Longer View: Is Industrial Metabolism [Really] the Problem?” in a session on “Traditions in Coping with Nature” at the international conference on Nature, Society and History: Long Term Dynamics of Social Metabolism sponsored by IFF-Social Ecology and several international foundations, Vienna, Austria, September-October 1999

1999 “Eating over the Boundary: Food from Beyond Natural Local Ecosystems” in the conference “Constructing and Deconstructing Frontiers: A Cross-Disciplinary Workshop” sponsored by the Department of Medieval Studies, Central European University, Budapest.

1999 “Exotic Food: Medieval Europeans eating fish from outside natural local ecosystems” at the tenth biennial meeting of the Fish Remains Working Group, International Congress of Archaeozoology, New York City, September 1999.

1999 “Foodways to Fishes: Doing Medieval Environmental History,” an invited lecture and seminar in the History Seminar Series, Queen’s University, Kingston, Ontario.

1999 “Frontier Fisheries for Medieval Consumers” opening lecture in the symposium “Beyond natural local ecosystems: Long-distance trading in fish and wood in the Netherlands, 1300-1700" sponsored by the Leerstoel Economische en Sociale Geschiedenis and Net Werk Stichting voor geschiedenis van hygiëne en milieu at the Vrije Universiteit Amsterdam.

1999 “Frontier Foods for Late Medieval Consumers: Culture, Economy, Ecology,” a lecture at the Institut für Wirtschafts- und Sozialgeschichte at the Universität Wien, Vienna, Austria, September 1999.

1999 “Marketing an Innovation, Visualizing a Craft: Images in the First Printed Book on Fishing, 1493-1557,” a public lecture sponsored by the Department of Medieval Studies, Central European University, Budapest.

1998 “Fish and Man: Changing Relations in Medieval Central Europe” an invited presentation to the annual meeting of the Österreichische Gesellschaft für Mittelalterarchäologie with the theme “Tier und Mensch im Mittelalter”, Thaya, Austria

1998 “Foodways to Fishes: Doing Medieval Environmental History,” an invited lecture and seminar in the series “Medieval Studies Beyond the Borders of the Humanities” at the Center for Medieval and Renaissance Studies, Ohio State University, Columbus.

1998 “How to Catch Fish: from Oral Exchanges to Printed Instructions,” an invited lecture and seminar at the Center for Medieval Studies, University of Minnesota (Twin Cities).

1998 “Protein, Penance, and Prestige: Medieval Demand for Fish” at a session on “The Infrastructures of Medieval Trade” at the 33d International Congress on Medieval Studies, Western Michigan University, Kalamazoo

1997 “Carp, Cods, Connections: New Fisheries in the Medieval European Economy and Environment,” an invited lecture and seminar at the University of Virginia, Charlottesville

1997 “New Fisheries in the Medieval Economy and Environment” at a session on “Animals in the Medieval Landscape” at the annual meeting, Medieval Academy of America, Toronto

1996 "Supply of fish to medieval towns" at a session on "Urban Economy and Society" at the 31st International Congress on Medieval Studies, Western Michigan University.

1995 "Changing Aquatic Ecosystems and Carp Culture in Medieval Europe," an invited lecture at the Institute of Ichthyology, University of Guelph.

1995 "Economic Development and Aquatic Ecosystems in Medieval Europe" at the session "L'histoire de l'environnement' in the 18th International Congress of Historical Sciences, Montréal.

1995 "Economic expansion, habitat destruction, and depletion of inland fisheries in medieval Europe," Fish Remains Working Group, International Congress of Archaeozoology, Madrid, Spain.

1995 "Protein, culture, and environment: the complex ecologies of fisheries in medieval Europe," an invited lecture at Brown University, Providence, Rhode Island.

1994 "Economic Development and Aquatic Ecosystems in Medieval Europe" at the 29th International Congress on Medieval Studies, Western Michigan University.

1993 "Late Medieval Germanies: Economic and Regional Perspectives" at the German-American Colloquium on German Medieval History, Medieval Institute, University of Notre Dame.

1993 "Medieval Cistercian Fisheries; Natural and Artificial" at "L'espace cistercien: Colloque international", sponsored by the Council of Europe, Abbaye de Fontfroide (Narbonne), France.

1993 "Medieval Society and Aquatic Ecosystem at Tegernsee" at the 28th International Congress of Medieval Studies, Western Michigan University.

1993 "Remains and Verbal Evidence of Carp (Cyprinus carpio) in Medieval Europe," Fish Remains Working Group, International Congress of Archaeozoology, Leuven, Belgium

1991 "Artorius Rex Britanniae from a Contemporary Witness" Annual Meeting, Societas Fontibus Historiae Medii Aevi Inveniendis.

1991 "The Craft of Fishing Alpine Lakes, ca. AD. 1500." Fish Remains Working Group, International Congress of Archaeozoology, Schleswig, Germany.

1991 "Traditional oral practice and literate culture in the first printed book on fishing" at the 26th International Congress on Medieval Studies, Medieval Institute, Western Michigan University, Kalamazoo.

1990 "A Comparative Approach to Socio-Economic Changes on the Frontiers of Latin Christendom" session on Medieval Frontiers and Beyond at the 25th International Congress of Medieval Studies, Western Michigan University.

1990 "A Fine Kettle of Fish: The Problematic Development of Pisciculture in Medieval Europe," session on Estate Management and Managers in the Pre-Industrial European Countryside at the 15th Annual Meeting, Social Science History Association.

1989 "Carpes pour le duc...: the operation of fish ponds at La Perriére-sur-Saône, Burgundy, 1338-52." Fish Remains Working Group, International Congress of Archaeozoology, Gothenburg, Sweden.

1987 "Knightly Families and their Properties around Wrocław," University of British Columbia Medieval Workshop on Dynasties.

1987 "Pike (Esox lucius) in late Medieval Culture: from Illiterate Empiricism to Literate Traditions,": International Congress of Archaeozoology Fish Remains Working Group, University of York, England.

1987 "Pike (Esox lucius) in Medieval European Culture," Tenth Annual Conference, Society of Ethnobiology.

1986 "Family and Property among the Elite of Late Medieval Wrocław" delivered to the history seminar, Instytut Historii Kultury Materialnej, Polska Akademia Nauk, Warsaw.

1985 "Adventures with Arthur: The Historian's Questions," session on Teaching Chivalry, 20th International Congress on Medieval Studies, Medieval Institute, Western Michigan University.

1984 "Fishing for Sport in Medieval Europe: New Evidence and an Interpretation," session on Medieval Societies and Natural Environments, 19th International Congress on Medieval Studies, Medieval Institute, Western Michigan University.

1984 "Teaching Critical Skills in Beginning History Courses at York," Fourth Annual Conference on Teaching and Learning in Post-Secondary Education, University of Western Ontario.

1983 "Family and Property among the Elite of Late Medieval Wrocław," University of British Columbia Medieval Workshop on Late Medieval Urban Institutions.

1982 "Default on Peasant Obligations in the Wrocław Duchy, 1425-1480: Social Resistance or Economic Distress?" session on Medieval Poland, 17th International Congress on Medieval Studies, Medieval Institute, Western Michigan University.

1982 "Forms of Dominance, Community Resistance, and Collaboration in a Late Medieval Principality of East-Central Europe," at Yale University Spring Colloquium: Peasantry: Domination and Resistance.

1981 "Outsiders by birth and blood: ideology and reality around the periphery of medieval European culture," Annual Medieval Symposium, Scarborough College, University of Toronto.

1981 "The Uses of Institutional Innovation: Locatio of Villages with German Law in the Duchy of Wrocław, 1220-1395," session on The Medieval Frontier: Ideas and Institutions, Sixteenth International Congress on Medieval Studies, Medieval Institute, Western Michigan University.

1980 "Credit and Debt in the Rural Society of the Wrocław Duchy," session on Late Medieval Agrarian History, Annual Meeting, American Historical Association.

1980 "The Distribution of Lordships and the Coming of Serfdom to East-Central Europe". Fifteenth International Congress on Medieval Studies, Medieval Institute, Western Michigan University.

1979 "At the Fringes of the Medieval West: Intercultural Contacts and their Effects". Fourteenth International Congress on Medieval Studies, Medieval Institute, Western Michigan University.

1978 "Lineage, Property, and Power among the Knightly Nobility of the Fourteenth Century Wrocław Duchy". Thirteenth International Congress on Medieval Studies, Medieval Institute, Western Michigan University.

1976 "At the Intersection of Agriculture and Commerce: Rural Markets and Traders around Wrocław in the Fourteenth Century". Eleventh International Congress on Medieval Studies, Medieval Institute, Western Michigan University.

1974 "Between Lord and Peasant: On the Socio-Economic Role of the Schultz in the German Law Village". Ninth International Congress on Medieval Studies, Medieval Institute, Western Michigan University.

1973 "Between Lord and Peasant: The Role of the Schultz in The German Law Village": Medieval House, University of Rochester.

1973 "The Systematic Study of Documentary Series: A Methodological Example in the Medieval Countryside"; Eighth Congress on Medieval Studies, Medieval Institute, Western Michigan University.

1972 "Control of Local Government in the Duchy of Wrocław, 1336-1530"; session on East-Central Europe: Crown and Diet, University of British Columbia History Workshop, Kingship and Estates in the Later Middle Ages.

1972 "Population Growth, Resource Limits, and Communal Control: On the Origins of Common Field Agriculture in Medieval Europe"; Special Conference on Economic Issues in European Agrarian History, Yale University.

1972 "Warfare, Weather, and a Rural Economy: The Duchy of Wrocław in the Mid-Fifteenth Century"; Seventh Congress on Medieval Studies, Medieval Institute, Western Michigan University.

1971 "Common-Field Institutions and Medieval Population Growth", Workshop on Peasants in Europe, Council for European Studies.

1971 "Postwar Studies in the Demography of Medieval Poland: A Review and Evaluation"; Second Congress of Scientists and Scholars, Polish Academy of Arts and Sciences in America.

1971 "The Changing Class Structure of Landlords in the Duchy of Wrocław in the Later Middle Ages", Session on Computer Techniques in Medieval Social History, Annual Meeting, American Historical Association.